This application claims the benefit of Japanese Patent application Nos.11-083899 and 2000-058899 which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a color separating prism or a color separating and composing prism for color-separating a white light into a red component light, green component light, and blue component light (hereinafter called the R light, G light, and B light, respectively) or for color-composing the R light, the G light and the B light into one light, a full color projection display apparatus provided with reflection-type light valves respectively for the R light, the G light, and the B light, for modulating and emitting polarized light beams of the respective colors entering the respective light valves, for color-composing the respective modulated color light beams from the light valves through the color separating and composing prism so as to analyze to extract the color-composed light by use of an analyzing optical system, and for projecting the analyzed light by use of a projection lens, as well as a camera provided with such prism.
2. Related Background Art
As a conventional projection display apparatus, there is known, for example, a full color projection display apparatus disclosed in Japanese Patent No. 2505758. FIG. 9 is a diagram for showing the constitution of the projection display apparatus disclosed in FIG. 1 of the above patent. The conventional apparatus will be described below with reference to this diagram.
A light source beam emitted from a light source 23 is converted into a substantially parallel light beam through a shaping lens 22 to enter a polarizing beam splitter 21. The light source beam entering the polarizing beam splitter 21 is polarized and split into an S-polarized light which is reflected by a polarization and separation unit of this polarizing beam splitter and a P-polarized light which progresses through this polarization and separation unit. The S-polarized light is emitted from the polarizing beam splitter 21 to enter a color separating and composing prism consisting of a prism 11A, a prism 11B, and a prism 11C. Note that this color separating and composing prism comprises a dichroic film formed on a surface 11e of the prism 11A for reflecting the B light and transmitting the G light and the R light and another dichroic film formed on a joint surface between the prism 11B and the prism 11C for reflecting the R light and transmitting the G light. In addition, a gap is formed between the prism 11A and the prism 11B.
The light beam entering from the surface 11a of the prism 11A progresses through the prism 11A, and enters the B light reflecting dichroic film formed on the surface 11e, and is color-separated into the B light to be reflected, and a mixed light of the R light and the G light which are transmitted through this dichroic film to enter the prism 11B through the gap. The B light which is reflected by the B light reflecting dichroic film progresses through the prism 11A to be totally reflected by the surface 11a, and further progresses to exit from an exit surface 11b, and then enters a B light reflection-type light valve 12 which is provided in the vicinity of the exit surface. On the other hand, the mixed light of the transmitted R light and G light enters an R light reflecting dichroic film. The R light reflected by this film progresses through the prism 11B and is totally reflected by an entrance surface of the prism 11B and then exits from the exit surface 11c to enter an light valve 13 for the R light which is provided in the vicinity of the exit surface. The G light progressing through the prism 11C continues to progress through the prism 11C as it is to exit from a surface 11d, and enters a G light reflection-type light valve 14 which is provided in the vicinity of the exit surface.
The S-polarized light incident on the light valve of each color is subjected to modulation by the use of a color signal of the color, and a predetermined part of this light is converted into a P-polarized light, and is reflected as a mixed light with the S-polarized light which is a non-modulated light, to exit therefrom. The mixed light emitted from each light valve goes back in the above optical path to exit as a color composed light from the surface 11a of the prism 11A. This color composed light re-enters the polarizing beam splitter 21, whereby only the P-polarized light which is a modulated light of each color is analyzed and extracted as a transmitted light from the polarizing beam splitter. The analyzed light enters a projection lens 24 to form a full color projection image on a screen 25.
However, the conventional projection display apparatus mentioned above has a problem that pixels of the three light valves for the R light, the G light and the B light are projected on the screen in a shifted manner due to a change in the environment, vibration, or the like, that is, a so-called registration shift is generated. The present inventor has studied and examined a registration shift generated in the above projection display apparatus, to clarify the cause thereof. As a result, he found that such registration shift is caused by the air gap between the prism 11A and the prism 11B and a space between the polarizing beam splitter 21 and the prism 11A.
More specifically, a relative positional relation between each prism member of the composite prism and the polarizing beam splitter for forming the gap or the space is changed due to a change in the ambient temperature, a vibration, or the like, thereby causing such registration shift.
An object of the present invention is to provide a color separating prism with an improved arrangement of prisms or the like having the above gap or space in the color separating prism, to the exclusion of the registration shift, and to provide a projection display apparatus in which the composing prism and the polarizing beam splitter are used in combination, to the exclusion of the registration shift.
Another object of the present invention is to provide a camera which is capable of always obtaining a shot image having an excellent contrast.
In order to achieve the above objects, according to the present invention, there is provided a color separating prism which comprises:
a first prism provided with a first surface on which a light is incident, a second surface having a first color reflecting dichroic film for reflecting a first color light (B light) and transmitting a second color light (R light), and a third surface for emitting the first color light (B light);
a second prism provided with a first surface for transmitting the second color light (R light) which is transmitted through the second surface of the first prism, a second surface for reflecting the second color light (R light), and a third surface for emitting the second color light (R light) which is totally reflected by the first surface after being reflected by the second surface, and integrally fixed to the first prism by an adhesive; and
a total reflection supporting layer provided between the second surface of the first prism and the first surface of the second prism to allow total reflection on the first surface of the second prism.
In a preferred embodiment of the present invention, a refractive index of the total reflection supporting layer is preferably lower than that of the second prism.
Also, in a preferred embodiment of the present invention, the total reflection supporting layer is preferably an adhesive for binding the first prism to the second prism.
Also, in a preferred embodiment of the present invention, an absolute value of a photoelastic constant of a glass material for forming the first prism and the second prism is preferably within a range of 1.5xc3x9710xe2x88x928 cm2/N, at the wavelengths of the first color light (B light) and the second color light (R light).
According to the present invention, there is provided a color separating prism which comprises:
a first prism provided with a first surface on which a light is incident, a second surface having a first color reflecting dichroic film for reflecting a first color light (B light) and transmitting a second color light (R light) and a third color light (G light), and a third surface for emitting the first color light (B light);
a second prism provided with a first surface for transmitting the second color light (R light) and the third color light (G light) which are transmitted through the second surface of the first prism, a second surface having a second color reflecting dichroic film for reflecting the second color light (R light) and transmitting the third color light (G light), and a third surface for emitting the second color light (R light) which is totally reflected by the first surface after being reflected by the second surface, and integrally fixed to the first prism by an adhesive; and
a third prism provided with a first surface for transmitting the third color light which is transmitted through the second surface of the second prism and a second surface for emitting the third color light (G light), and integrally fixed to the second prism by an adhesive.
According to the present invention, there is provided a projection display apparatus, comprising:
a polarizing device which converts a light from a light source into a polarized light beam having a predetermined direction of oscillation;
a color separating optical system which color-separates the polarized light beam emitted from the polarizing device into a first color light (B light), a second color light (R light), and a third color light (C light);
a first reflection-type light valve which modulates the direction of oscillation of the first color light (B light) and reflects this light;
a second reflection-type light valve which modulates the direction of oscillation of the second color light (R light) and reflects this light;
a third reflection-type light valve which modulates the direction of oscillation of the second color light (G light) and reflects this light;
a color composing optical system which composes the lights emitted from the first reflection-type light valve, the second reflection-type light valve, and the third reflection-type light valve; and
an analyzing optical system which analyzes the light emitted from the color composing optical system,
wherein the color composing optical system further comprises:
a first prism provided with a first surface on which the polarized light beam emitted from the polarizing device is incident, a second surface having a first color reflecting dichroic film for reflecting the first color light (B light) and transmitting the second color light (R light) and the third color light (G light), and a third surface for emitting the first color light (B light);
a second prism provided with a first surface for transmitting the second color light (R light) and the third color light (G light) which are transmitted through the second surface of the first prism, a second surface having a second color reflecting dichroic film for reflecting the second color light (R light) and transmitting the third color light (G light), and a third surface for emitting the second color light (R light) which is totally reflected by the first surface after being reflected by the second surface, and integrally fixed to the first prism by an adhesive;
a third prism provided with a first surface for transmitting the third color light (G light) transmitted through the second surface of the second prism and a second surface for emitting the third color light (G light); and
a total reflection supporting layer provided between the second surface of the first prism and the first surface of the second prism to allow total reflection on the first surface of the second prism.
In a preferred embodiment of the present invention, a refractive index of the total reflection supporting layer is preferably lower than that of the second prism.
Also, in a preferred embodiment of the present invention, the total reflection supporting layer is preferably an adhesive for binding the first prism to the second prism.
Also, in a preferred embodiment of the present invention, an absolute value of a photoelastic constant of a glass material for forming the polarizing device, the first prism and the second prism is preferably within a range of 1.5xc3x9710xe2x88x928 cm2/N, at the wavelengths of the first color light (B light) and the second color light (R light).
Also, in a preferred embodiment of the present invention, it is preferable that the first prism is integrally fixed to the polarizing device by an adhesive, and there is further provided a second total reflection supporting layer between the polarizing device and the first surface of the first prism, for allowing total reflection on the first surface of the first prism.
In a preferred embodiment of the present invention, a refractive index of the second total reflection supporting layer is preferably lower than that of the first prism.
Also, according to the present invention, there is provided a projection display apparatus, comprising:
a polarizing device which converts a light from a light source into a polarized light beam having a predetermined direction of oscillation;
a color separating optical system which color-separates the polarized light beam emitted from the polarizing device into a first color light (B light), a second color light (R light), and a third color light (G light);
a first reflection-type light valve which modulates the direction of oscillation of the first color light (B light) and reflects this light;
a second reflection-type light valve which modulates the direction of oscillation of the second color light (R light) and reflects this light;
a third reflection-type light valve which modulates the direction of oscillation of the second color light (G light) and reflects this light;
a color composing optical system which composes the lights emitted from the first reflection-type light valve, the second reflection-type light valve, and the third reflection-type light valve; and
an analyzing optical system which analyzes the light emitted from the color composing optical system,
wherein the color composing optical system comprises:
a first prism provided with a first surface on which the polarized light beam emitted from the polarizing device is incident, a second surface having a first color reflecting dichroic film for reflecting the first color light (B light) and transmitting the second color light (R light) and the third color light (G light), and a third surface for emitting the first color light (B light), and integrally fixed to the polarizing device by an adhesive;
a second prism provided with a first surface for transmitting the second color light (R light) and the third color light (G light) which are transmitted through the second surface of the first prism, a second surface having a second color reflecting dichroic film for reflecting the second color light (R light) and transmitting the third color light (G light), and a third surface for emitting the second color light (R light) which is totally reflected by the first surface after being reflected by the second surface;
a third prism provided with a first surface for transmitting the third color light (G light) transmitted through the second surface of the second prism and a second surface for emitting the third color light (G light); and
a total reflection supporting layer provided between the polarizing device and the first surface of the first prism to allow total reflection on the first surface of the first prism.
Also, according to the present invention, there is provided a projection display apparatus, comprising:
a polarizing device which converts a light from a light source into a polarized light beam having a predetermined direction of oscillation;
a first prism provided with a first surface on which the polarized light beam emitted from the polarizing device is incident, a second surface having a first color reflecting dichroic film for reflecting the first color light (B light) and transmitting the second color light (R light) and the third color light (G light), and a third surface for emitting the first color light (B light), and integrally fixed to the polarizing device by an adhesive;
a second prism provided with a first surface for transmitting the second color light (R light) and the third color light (G light) which are transmitted through the second surface of the first prism, a second surface having a second color reflecting dichroic film for reflecting the second color light (R light) and transmitting the third color light (G light), and a third surface for emitting the second color light (R light) which is totally reflected by the first surface after being reflected by the second surface, and integrally fixed to the first prism by an adhesive;
a third prism provided with a first surface for transmitting the third color light (G light) which is transmitted through the second surface of the second prism and a second surface for emitting the third color light (G light), and integrally fixed to the second prism by an adhesive;
a first reflection-type light valve which modulates the direction of oscillation of the first color light (B light) emitted from the first prism and reflects this light;
a second reflection-type light valve which modulates the direction of oscillation of the second color light (R light) emitted from the second prism and reflects this light;
a third reflection-type light valve which modulates the direction of oscillation of the second color light (G light) emitted from the third prism and reflecting this light;
a color composing optical system which composes the lights emitted from the first reflection-type light valve, the second reflection-type light valve, and the third reflection-type light valve; and
an analyzing optical system which analyzes the light emitted from the color composing optical system.
Also, according to the present invention, there is provided a camera, comprising:
an image forming optical system which forms an image of an object to be photographed;
a first prism provided with a first surface on which a light from the image forming optical system is incident, a second surface having a first color reflecting. dichroic film for reflecting a first color light (B light) and transmitting a second color light (R light), and a third surface for emitting the first color light (B light);
a second prism provided with a first surface for transmitting the second color light (R light) which is transmitted through the second surface of the first prism, a second surface for reflecting the second color light (R light), and a third surface for emitting the second color light (R light) which is totally reflected by the first surface after being reflected by the second surface, and integrally fixed to the first prism by an adhesive;
a total reflection supporting layer provided between the second surface of the first prism and the first surface of the second prism to allow total reflection on the first surface of the second prism;
a first image pick-up device provided at an image position of the image forming optical system which picks up an image of the object corresponding to the first color light (B light) emitted from the first prism to output a first image pick-up signal; and
a second image pick-up device provided at the image position of the image forming optical system which picks up an image of the object corresponding to the second color light (R light) emitted from the second prism to output a second image pick-up signal.
In a preferred embodiment of the present invention, a refractive index of the total reflection supporting layer is preferably lower than that of the second prism.
Also, in a preferred embodiment of the present invention, the total reflection supporting layer is preferably an adhesive for binding the first prism to the second prism.
Also, in a preferred embodiment of the present invention, it is preferable to further comprise an image signal generating circuit 110 for generating an image signal on the basis of the first image pick-up signal and the second image pick-up signal.
Also, according to the present invention, there is provided a method of manufacturing a color separating prism comprising the steps of:
providing a first prism with a first surface on which a light is incident, a second surface having a first color reflecting dichroic film for reflecting a first color light (B light) and transmitting a second color light (R light), and a third surface for emitting the first color light (B light);
providing a second prism with a first surface for transmitting the second color light (R light) which is transmitted through the second surface of the first prism, a second surface for reflecting the second color light (R light), and a third surface for emitting the second color light (R light) which is totally reflected by the first surface after being reflected by the second surface, integrally fixed to the first prism by an adhesive; and
providing a total reflection supporting layer between the second surface of the first prism and the first surface of the second prism to allow total reflection on the first surface of the second prism.
In a preferred embodiment of the present invention, a refractive index of the total reflection supporting layer is preferably lower than that of the second prism.
Also, in a preferred embodiment of the present invention, the total reflection supporting layer is preferably an adhesive for binding the first prism to the second prism.
Also, in a preferred embodiment of the present invention, an absolute value of a photoelastic constant of a glass material for forming the polarizing device, the first prism and the second prism is preferably within a range of 1.5xc3x9710xe2x88x928 cm2/N, at the wavelengths of the first color light and the second color light.
According to the present invention, there is provided a method of manufacturing a color separating prism comprising the steps of:
providing first prism with a first surface on which a light is incident, a second surface having a first color reflecting dichroic film for reflecting a first color light and transmitting a second color light and a third color light, and a third surface for emitting the first color light;
providing a second prism with a first surface for transmitting the second color light and the third color light which are transmitted through the second surface of the first prism, a second surface having a second color reflecting dichroic film for reflecting the second color light and transmitting the third color light, and a third surface for emitting the second color light which is totally reflected by the first surface after being reflected by the second surface, integrally fixed to the first prism by an adhesive; and
providing a third prism with a first surface for transmitting the third color light transmitted through the second surface of the second prism and a second surface for emitting the third color light, integrally fixed to the second prism by an adhesive.
According to the present invention, there is provided a method of manufacturing a projection display apparatus, comprising the steps of:
providing a polarizing device which converts a light from a light source into a polarized light beam having a predetermined direction of oscillation;
providing a color separating optical system which color-separates the polarized light beam emitted from the polarizing device into a first color light, a second color light, and a third color light;
providing a first reflection-type light valve which modulates the direction of oscillation of the first color light and reflects this light;
providing a second reflection-type light valve which modulates the direction of oscillation of the second color light and reflects this light;
providing a third reflection-type light valve which modulates the direction of oscillation of the second color light and reflects this light;
providing a color composing optical system which composes the lights emitted from the first reflection-type light valve, the second reflection-type light valve, and the third reflection-type light valve;
providing an analyzing optical system which analyzes the light emitted from the color composing optical system,
wherein the step of providing the color composing optical system further comprises the steps of:
providing a first prism with a first surface on which the polarized light beam emitted from the polarizing device is incident, a second surface having a first color reflecting dichroic film for reflecting the first color light and transmitting the second color light and the third color light, and a third surface for emitting the first color light;
providing a second prism with a first surface for transmitting the second color light and the third color light which are transmitted through the second surface of the first prism, a second surface having a second color reflecting dichroic film for reflecting the second color light and transmitting the third color light, and a third surface for emitting the second color light which is totally reflected by the first surface after being reflected by the second surface, integrally fixed to the first prism by an adhesive;
providing a third prism with a first surface for transmitting the third color light transmitted through the second surface of the second prism and a second surface for emitting the third color light; and
providing a total reflection supporting layer between the second surface of the first prism and the first surface of the second prism to allow total reflection on the first surface of the second prism.
In a preferred embodiment of the present invention, a refractive index of the total reflection supporting layer is preferably lower than that of the second prism.
Also, in a preferred embodiment of the present invention, the total reflection supporting layer is preferably an adhesive for binding the first prism to the second prism.
Also, in a preferred embodiment of the present invention, an absolute value of a photoelastic constant of a glass material for forming the polarizing device, the first prism and the second prism is preferably within a range of 1.5xc3x9710xe2x88x928 cm2/N, at the wavelengths of the first color light and the second color light.
Also, in a preferred embodiment of the present invention, it is preferable that the first prism is integrally fixed to the polarizing device by an adhesive, and there is further comprised the step of providing a second total reflection supporting layer between the polarizing device and the first surface of the first prism, for allowing total reflection on the first surface of the first prism.
In a preferred embodiment of the present invention, a refractive index of the second total reflection supporting layer is preferably lower than that of the first prism.
Also, according to the present invention, there is provided a method of manufacturing a projection display apparatus, comprising the steps of:
providing a polarizing device which converts a light from a light source into a polarized light beam having a predetermined direction of oscillation;
providing a color separating optical system which color-separates the polarized light beam emitted from the polarizing device into a first color light, a second color light, and a third color light;
providing a first reflection-type light valve which modulates the direction of oscillation of the first color light and reflects this light;
providing a second reflection-type light valve which modulates the direction of oscillation of the second color light and reflects this light;
providing a third reflection-type light valve which modulates the direction of oscillation of the second color light and reflecting this light;
providing a color composing optical system which composes the lights emitted from the first reflection-type light valve, the second reflection-type light valve, and the third reflection-type light valve; and
providing an analyzing optical system which analyzes the light emitted from the color composing optical system,
wherein the step of providing the color composing optical system further comprises the steps of:
providing a first prism with a first surface on which the polarized light beam emitted from the polarizing device is incident, a second surface having a first color reflecting dichroic film for reflecting the first color light and transmitting the second color light and the third color light, and a third surface for emitting the first color light, integrally fixed to the polarizing device by an adhesive;
providing a second prism with a first surface for transmitting the second color light and the third color light which are transmitted through the second surface of the first prism, a second surface having a second color reflecting dichroic film for reflecting the second color light and transmitting the third color light, and a third surface for emitting the second color light which is totally reflected by the first surface after being reflected by the second surface;
providing a third prism with a first surface for transmitting the third color light transmitted through the second surface of the second prism and a second surface for emitting the third color light; and
providing a total reflection supporting layer between the polarizing device and the first surface of the first prism to allow total reflection on the first surface of the first prism.
Also, according to the present invention, there is provided a method of manufacturing a projection display apparatus, comprising the steps of:
providing a polarizing device which converts a light from a light source into a polarized light beam having a predetermined direction of oscillation;
providing a first prism with a first surface on which the polarized light beam emitted from the polarizing device is incident, a second surface having a first color reflecting dichroic film for reflecting the first color light and transmitting the second color light and the third color light, and a third surface for emitting the first color light, integrally fixed to the polarizing device by an adhesive;
providing a second prism with a first surface for transmitting the second color light and the third color light which are transmitted through the second surface of the first prism, a second surface having a second color reflecting dichroic film for reflecting the second color light and transmitting the third color light, and a third surface for emitting the second color light which is totally reflected by the first surface after being reflected by the second surface, integrally fixed to the first prism by an adhesive;
providing a third prism with a first surface for transmitting the third color light transmitted through the second surface of the second prism and a second surface for emitting the third color light, integrally fixed to the second prism by an adhesive;
providing a first reflection-type light valve which modulates the direction of oscillation of the first color light emitted from the first prism and reflecting this light;
providing a second reflection-type light valve which modulates the direction of oscillation of the second color light emitted from the second prism and reflects this light;
providing a third reflection-type light valve which modulates the direction of oscillation of the second color light emitted from the third prism and reflects this light;
providing a color composing optical system which composes the lights emitted from the first reflection-type light valve, the second reflection-type light valve, and the third reflection-type light valve; and
providing an analyzing optical system which analyzes the light emitted from the color composing optical system.
Also, according to the present invention, there is provided a method of manufacturing a camera, comprising the steps of:
providing an image forming optical system which forms an image of an object to be photographed;
providing a first prism with a first surface on which a light from the image forming optical system is incident, a second surface having a first color reflecting dichroic film for reflecting a first color light and transmitting a second color light, and a third surface for emitting the first color light;
providing a second prism with a first surface for transmitting the second color light which is transmitted through the second surface of the first prism, a second surface for reflecting the second color light, and a third surface for emitting the second color light which is totally reflected by the first surface after being reflected by the second surface, integrally fixed to the first prism by an adhesive;
providing a total reflection supporting layer between the second surface of the first prism and the first surface of the second prism to allow total reflection on the first surface of the second prism;
providing a first image pick-up device at an image position of the image forming optical system which picks up an image of the object corresponding to the first color light emitted from the first prism to output a first image pick-up signal; and
providing a second image pick-up device at the image position of the image forming optical system which picks up an image of the object corresponding to the second color light emitted from the second prism to output a second image pick-up signal.
In a preferred embodiment of the present invention, a refractive index of the total reflection supporting layer is preferably lower than that of the second prism.
Also, in a preferred embodiment of the present invention, the total reflection supporting layer is preferably an adhesive for binding the first prism to the second prism.
Also, in a preferred embodiment of the present invention, it is preferable to further comprise the step of providing an image signal generating circuit which generates an image signal on the basis of the first image pick-up signal and the second image pick-up signal.